Is it possible to somehow fix this broken cable-stop on the chain-stay? I don't know enough about frame construction, was this welded on with a big glob of metal?
Why couldn't you just drill-out, tap and screw in a new one?

The easiest way to deal with this is to file off the stump and use a clamp-on cable stop:

There's a pretty good size of metal there. That strap style stop would obviously work but it seems like a rather cobbly looking option.

Another option is to clean it up and silver solder on a new stop which you'd buy from a frame parts supplier.

Yet another way is to make up your own U shaped sheet metal stop and pop rivet it on. Such a stop would be best made from 16ga steel for good strength and long term durability. It would be done as a !_! shape wiht holes in all three sides. One upright would be a small hole which fits the cable nicely. Opposite that would be a hole for the housing ferrule to fit through. The hole in the base would be to fit a 3/32 or 1/8 diameter pop rivet. Or you can get fancier if you have the tools and skills to carve something out of a different metal and rivet it on. Just do the job with some sensitivity to the frame. There's not a lot of metal thickness in the stays other than where that little blob of welding or brazing is located.

A frame builder could easily fix that for you. It's not a big deal for them to remove the stub and braze a new stop on in the same spot.

If a new one is brazed on the chrome will be toast.

This was my understanding of the welding process as well.

I think the clamp-on cable-stops are pretty ugly and over-sized for what they have to accomplish.

I see some small holes in the seat-stays and forks for welding gas expansion but I'd be a little concerned about drilling a hole big enough for a pop-rivet.
Anyone have some actual experience doing this?

The original stop was brazed in and there is no hole or threaded stop... John's suggestion makes the most sense as filing away the old stop will not affect the integrity of the stay and a clamp on stop is by far the simplest solution.

Don't know of anyone that make a stop that could be threaded in as they are very small fittings and whoever installed the first one went a little crazy with the welding... that is overkill for a part that sees very little load stress.

I am with John and Sixty Fiver, on this. if that was my frame I would file.dremel off the ugly rectangle portion of that brazeon and put a little clear nailpolish on to seal it. then put the clamp on stop right behind it, so the cable kinda cover the round spot.

if one of you LBSs has that clamp in stock you can be riding that frame this Sunday. a frame shop may take a few months.

I saw that frame before what is it?

You can improve the looks of the clamp-on cable stop by just simply changing the mounting bolt to a nice Allen head one with a nice acorn/domed nut at the back. I think Allen head bolts always adds good looks to anything you use it on.

Chombi

It's my, five days since purchase, Legnano.
It needs just about everything except headset, BB-cups and wheels.
Anyone want to help me with a set of parts-group?
My other bike is French, so I don't have any Italian sized stuff.